Capt. Daryl Hendricks said Castillo Mota went into his ex-girlfriend's second-floor apartment when she wasn't there and used a lighter to ignite the bedding on her bed. He was seen leaving the apartment shortly before the fire spread, Hendricks said.

The two-alarm fire broke out around 2:45 a.m. Firefighters arrived to find flames shooting out of two second-floor windows at the corner of Seventh and Liberty streets. The fire started in the second-floor apartment in the front of the building.

Fire officials said everyone made it out safely because smoke alarms woke them. Two adults living in the adjacent building at 503 N. Seventh, were also displaced.

Castillo Mota was arrested at 5 p.m. Wednesday and charged with arson, burglary, criminal trespassing, risking or causing a catastrophe and reckless endangerment. He was arraigned by District Judge Ron Manescu and sent to Lehigh County Prison under $125,000 bail.